As a relative newcomer to the game, I find that when I get killed I frequently don’t have any really good idea of what did me in. It often happens so quickly and/or while so much stuff is going on that there isn’t really even time to identify the source of the damage, let alone its type etc.
Some sort of combat log would be useful. Ideally written to disk and/or exposed to Lua.
(Apologies if there already is such a mod: I haven’t managed to find it yet.)